The ink acceptor layer has been coated on a surface of a recording paper used for printers of an electric instrument etc., in order to raise the printing effect, i.e. clear nature and fixing property etc. of ink. As a material of this ink acceptor layer, the materials having good fixing property without blotting with ink have been used, and the fine silica powder also has been used as one of said materials. However, when the fine silica powder is used for the ink-jet printer, which has been widely spread recently, the blotting with ink may occur on the surface of the recording paper at the time of printing, so that its improvement is acquired.
Although various surface-modified treatments has been conventionally known about the fine silica powder, it has been not known yet that the process, in which the printing effect is improved basing on the specific index about the surface-treatment. Therefore, when some surface-modified fine silica powders are used as the material of the ink acceptor layer, the printing effect cannot be improved sufficiently. Especially, in the printing materials used for ink-jet printing, sufficient effect may not be obtained.
Moreover, although the conventional fine silica powder has been used as a viscosity increasing reagent, when said fine silica powder is added to a coating material or printing ink etc., there are some problems in which the viscosity of slurry becomes high rapidly and the viscosity preparation becomes difficult when the much amount of fine silica powders is added.